1. Go to Data Management > Import / Export.
  2. Click on the All Data Sync Operations tab.
  3. Search for the desired sync.
  4. Click on the Schedule link.
  5. Modify the list of email address in the Email Notifications box.
  6. Click the Save or Finish link.

Note that if this does not work, you may need to temporarily modify the Schedule, click Save, change the Schedule back, and click Save again.